%YAML 1.1
---
$schema: "http://stsci.edu/schemas/yaml-schema/draft-01"
id: "http://stsci.edu/schemas/asdf/transform/cylindrical_equal_area-1.0.0"
title: |
  The cylindrical equal area projection.

description: |
  Corresponds to the `CEA` projection in the FITS WCS standard.

  The pixel-to-sky transformation is defined as:

  $$\phi &= x \\
  \theta &= \sin^{-1}\left(\frac{\pi}{180^{\circ}}\lambda y\right)$$

  And the sky-to-pixel transformation is defined as:

  $$x &= \phi \\
  y &= \frac{180^{\circ}}{\pi}\frac{\sin \theta}{\lambda}$$

  Invertibility: All ASDF tools are required to provide the inverse of
  this transform.

allOf:
  - $ref: "cylindrical-1.0.0"
  - type: object
    properties:
      lambda:
        type: number
        description: |
          Radius of the cylinder in spherical radii, default is 1.
        default: 1
...
